Hydrogen production through water electrolysis stands as a potential remedy for the problem of curtailment, which refers to the deliberate downward adjustment of output power below capacity for the purpose of balancing supply and demand. This study demonstrates how comprehensive system modeling can be used to a priori assess the economics of producing green hydrogen from curtailed renewable energy of solar and wind. A case study is presented to demonstrate how actual meteorological data are utilized to anticipate the quantity of renewable energy throughout the year, which in turn is used to estimate the capacity factor and LCOH (Levelized Cost of Hydrogen) of a renewable energy/water electrolysis system. The base case of a renewable energy source of 100 MW capacity coupled with a 20 MW hydrogen production system and 20 MW transmission to the grid shows an LCOH of 5.9 USD/kg with a capacity factor of 25%. Sensitivity analysis is carried out to examine the impact of electrolyser size and the composition of renewable energy source on its capacity factor and economic feasibility. The results demonstrate that the capacity factor of an electrolysis system is not directly proportional to the renewable energy capacity but depends on the its designed capacity as well as the climate pattern and the mix ratio between solar and wind energy. Though the effect of the electrolyser’s operating range is found insignificant in a part-load operation but not in an overload operation. In addition, the effects of the capital cost, system efficiency, and electricity price on LCOH are assessed.